Vaccine Effective Against Common Meningococcal Strains

By staff

A four-component vaccine appears effective against more than 90% of bacterial strains causing a common type of invasive serogroup B meningococcal disease in young adults and children, a new study reports.

The article in mSphere, an open access journal from the American Society for Microbiology, reports a test predicted that 91% of those bacterial strains causing meningococcal disease in the United States would be covered by the MenB-4C vaccine. Estimated coverage ranged from 88% to 97% each year, according to study authors led by CDC researchers.

Serogroup B strains of the bacteria caused about 40% of invasive meningococcal disease in all age groups, and more than 60% in infants, according to background information in the report.

The vaccine, marketed as Bexsero, is from GlaxoSmithKline, which participated in the research. The product was approved by the FDA in 2015 for use in Americans aged 10 to 25 years.

Because efficacy studies to demonstrate the benefit of meningococcal vaccines are not feasible due to the relatively low incidence of the disease, the Meningococcal Antigen Typing System (MATS) was employed to estimate the coverage potential of the MenB-4C vaccine. It contains four antigens to prevent invasive meningococcal disease caused by the serogroup B form of the bacteria Neisseria meningitidis: factor H binding protein (fHBP); Neisserial heparin binding protein (NHBA); Neisserial adhesin A (NadA); and PorA-containing outer membrane vesicles.

Tested were 442 N meningitidis serogroup B samples collected by the CDC from 2000 to 2008. Results indicate that more than half of the covered strains could be targeted by two or more antigens in the vaccine. Specifically, NHBA covered 83% of the strains, fHBP covered 53% of the strains, PorA covered 5.9% of the strains, and NadA covered 2.5% of the strains.

“We are very pleased to see that it looks like the vaccine has the potential to cover most of the strains of meningococcal Group B bacteria currently circulating in the U.S.,” said lead author Gowrisankar Rajam, PhD, a health scientist at the CDC. “However, we need to continue our analysis to assess the coverage of currently circulating strains in the U.S. We are confident the MATS technique will be very useful at detecting any changes in bacterial expression of these antigens.”

“Although this study was limited to the evaluation of NmB strains circulating up to 2009, the stability of the strain coverage prediction over the nine-year period investigated suggests that no major differences should be expected in the ensuing years,” study authors add. “Also, all genetic lineages significantly represented in the country were covered at levels of >85%, suggesting that temporal oscillations in the frequency of clonal complexes would not affect significantly the MenB-4C strain coverage.”